The Different Types of Laxatives and How They Work

When dealing with a stubborn stool or constipation the variety of treatments available can often feel overwhelming; hardly ideal when all you want is to find the most effective and comfortable way of restoring your natural bowel movements.

Each method is slightly different, and one may be more suitable for you depending on your specific circumstances or preferences. Perhaps time is of the essence, for example, or perhaps you are willing to wait a little longer for a remedy that eases your symptoms more gently and gradually.

Whatever your needs, this article explores the four main types of laxatives available, how they work and, ultimately, why some may occasionally be preferable to others.

When lifestyle changes such as eating a higher-fibre diet, drinking more fluids or increasing exercise have failed to shift your stubborn stool, many consider bulk-forming laxatives to be the first port of call.

Bulk-forming laxatives are treatments that contain a high quantity of fibre – a material which your body cannot entirely digest, so helps bulk out your stool – such as ispaghula husk, psyllium husk, or methylcellulose. These are often taken as a high-fibre drink or a capsule which is swallowed.

By increasing the volume of your poo, fibre helps to stimulate your bowel to make your stool easier to pass. You can expect a bulk-forming laxative to take effect in 2-3 days.¹

Osmotic laxatives contain an active ingredient such as macrogol or lactulose, which works to hydrate a stubborn stool so that it becomes softer and easier to pass.

In Movicol^®, for example, macrogol binds with water and draws it into your stools so that your poo becomes hydrated, ensuring that it’s no longer hard, dry and difficult to pass.² A stubborn stool can occur when moisture is lost from the stool to the rest of your body, so osmotic laxatives help to restore this balance by bringing your poo closer to having a healthy 75% water content. ³

Most users experience relief from osmotic laxatives within 24-48 hours*. They often come in a sachet of powder which you dissolve in water and drink.

A more rapid and forceful form of constipation treatment, stimulant laxatives like bisacodyl or senna get to work by directly stimulating the walls of your intestines, causing them to contract more frequently and powerfully to get stubborn stools moving through your digestive system.

Stimulant laxatives are one of the more potent and time-efficient methods of relief, generally getting to work within 8-12 hours.⁴ However, because of their impact on the body, stimulant laxatives should only be used for short periods of time and are not suitable for people with chronic constipation. Long-term misuse can lead to your intestines losing their ability to function normally without the laxative.⁵

Treatments containing docusate or arachis oil work directly on the stool to allow water to enter your poo and make it softer and easier to pass. Stool softeners are generally more suited for use as a preventative measure rather than a treatment for acute constipation.⁶

Please refer to the relevant product’s patient information leaflet for more information on what they are indicated to treat.

Choosing the best laxative means choosing what is right for you and for the nature and severity of your stubborn stool, while taking your specific health conditions into account alongside how urgently you need relief. If in doubt, it’s always best to consult a medical professional before making an informed decision on which treatment option is right for you.

Date of Prep: 17.06.2024 | GL-GE-MOV-2400046

*Movicol^® results may take longer for some users.

^[1]  Laxatives. NHS. Page last updated 11 October 2022. Accessed here: https://www.nhs.uk/conditions/laxatives/

^[2] Schiller LR, Emmett M, Santa Ana CA, Fordtran JS. Osmotic effects of polyethylene glycol. Gastroenterology, 1988; 94: 933-941.

^[3] Rose C, Parker A, Jefferson B, et al. The characterization of Feces and urine: A review of the literature to inform Advanced Treatment Technology. Crit Rev Environ Sci Technol. 2015 Sep 2;45(17):1827-1879.

^[4] Laxatives. NHS. Page last updated 11 October 2022. Accessed here: https://www.nhs.uk/conditions/laxatives/

^[5]  Laxatives. Cleveland Clinic. Page last updated 10 July 2023. Accessed here: https://my.clevelandclinic.org/health/treatments/25121-laxatives

^[6]  Stool Softeners vs. Laxatives. Healthline. Page last updated 28 August 2016. Accessed here: https://www.healthline.com/health/constipation/stool-softeners-laxatives